Elite Drivo II Smart trainer vs Stages Power Meter Accuracy

At the beginning of my indoor training season (aka winter in Canada) I did an ftp test and was a little shocked to see that it was about 40watts lower than I expected (previously measure a few months earlier outside with a stages pm and didn’t feel I had lost much fitness, not 40 watts worth). Since I was just going to be training with power indoors for the winter I didn’t really care that it was so low as long as it was consistently increasing. Now, I just got my hands on an Elite Drivo II smart trainer and when observing the power numbers from this versus my stages pm the smart meter was about 40watts higher than my stages. Both were calibrated prior to using so which one is the accurate number?

Obviously, I really only care about consistency, but sometimes it’s also fun to compare numbers with my riding buddies for bragging rights (or to worry how quickly they will drop me come. Spring) …

So, which is more accurate? Should I use this power match option? Is there a way to check that my stages pm is correct? Any, insight would be helpful.

The stages is probably more accurate, but it’s irrelevant as long as the one you pick is consistent.

The difference may also be way less than you wish for, due to drive train losses and the possibility of L\R imbalance

Elite claims +/- 0.5% accuracy for the Drivo II.

Stages claims +/- 1.5% accuracy for a Gen 3 Ultegra (you don’t mention which you have).

So, the Drivo II should be more “correct”. It uses a special Optical Torque Sensor that is crazy accurate and consistent. So unless it was damaged, it is likely correct.

Add the fact that it is effectively catching both sides, and the Stages is the one to question in terms of accuracy. You likely have some imbalance that is contributing to the difference, in addition to the expanded tolerance range for the Stages.

You mention 40w, but at what power output? We need to look at the power output as part of the equation in evaluation of the tolerance ranges to see if they are in spec, but possibly at opposite ends of the spectrum.

At 200w:

  • The Drivo II would have a 199-201w range.
  • The Stages would have a 197-203w range.

So the max delta would be 4w in that case, assuming everything else is equal.

1 Like

I have gen 3 ultegra stages and the 40 watt difference is just a estimation based on observation of a brief test between 200 and 300 watts - I know I should do a much more controlled experiment. I have assumed that since getting back into indoor training my numbers have “felt” low and that maybe there is something wrong with my stages. Any suggestions on how to check this without sending it back?

Again, I am not too concerned as I will continue to use the stages for training and this consistency is what is important for improvements. I am a little concerned as I am toying with the idea of getting another pm for my cx/gravel bike.

You should probably contact Stages to get the best recommendation for any test you can try to validate.

If you have access to a friend with another accurate smart trainer or power meter pedals, you could try a comparison with those, the Stages and Drivo II to get 3 simultaneous data sets.

Check out DCRainmaker’s Analyzer. https://analyze.dcrainmaker.com/ Pull the 2 files from your different power meters, match them up and compare them. That is the objective way to help you get to a solution. As a subjective (n=1) account, I will let you know how I am with my stages. I have a very lazy left leg until I get into Tempo, or so, and it starts doing a bit of work. So, under that point, I am ~25 points low compared to my PT. Above Tempo, it matches in the range (1% - 2%, or so) that it should. I use an Elite Direto and that is rock solid with another PM (Quarq Elsa). I use the Direto 100% of the time when training indoors. All my testing and training have been on that Direto. If you use the same power meter, the results should always be the same, as long as the power meter gives consistent readings.

Does a stages ever read correctly?

They’ve thrown their hands up in the air with the Stages Gen III Dual I have here… which has pissed me off a little. It’s a beautiful DuraAce crankset… that’s useless to me.

Anyhow OP - Let us know how you get on.


Just to add another reference point, just fitted DA stages and compared to my 2017 kickr and its very closely matched (note Im very even between L/R)

I found with my stages that i was getting frequent signal drop outs.

When i had smoothing applied on my garmin it would show a consistently lower power number (compared to my smart trainer) because of this.

I moved my head unit onto my stem and it got better but was still not great. I have since moved to a power2max meter and it aligns very closely with my trainer.

Wow, that really stinks, Shane. Super lame from them.